package image

import (
	"bytes"
	"context"
	"encoding/base64"
	"fmt"
	"image"
	"io"
	"os"
	"strconv"
	"strings"
	"testing"
	"testing/synctest"
	"time"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func TestService_SaveAndLoad(t *testing.T) {
	store := StoreMock{
		SaveFunc: func(string, []byte) error {
			return nil
		},
		LoadFunc: func(string) ([]byte, error) {
			return nil, nil
		},
	}
	svc := NewService(&store, ServiceParams{MaxSize: 1500, MaxWidth: 32, MaxHeight: 32})

	err := svc.SaveWithID("test_id", gopherPNG())
	assert.NoError(t, err)
	assert.Equal(t, 1, len(store.SaveCalls()))
	assert.Equal(t, "test_id", store.SaveCalls()[0].ID)

	img, err := svc.Load("test_id")
	assert.NoError(t, err)
	assert.Nil(t, img)
	assert.Equal(t, 1, len(store.LoadCalls()))
	assert.Equal(t, "test_id", store.LoadCalls()[0].ID)
}

// the resized dimensions are what resize promises; the encoded length is whatever the compressor
// in the toolchain happens to produce, and pinning it fails on a go release that changes it
func TestService_Resize(t *testing.T) {
	img, err := readAndValidateImage(gopherPNG(), 1500)
	assert.NoError(t, err)
	assert.NotEmpty(t, img)

	img = resize(img, 32, 32)
	assertImageFits(t, img, 32, 32)
}

func TestService_ResizeJpeg(t *testing.T) {
	fh, err := os.Open("testdata/circles.jpg")
	defer func() { assert.NoError(t, fh.Close()) }()
	assert.NoError(t, err)

	img, err := readAndValidateImage(fh, 32000)
	assert.NoError(t, err)
	assert.NotEmpty(t, img)

	img = resize(img, 400, 300)
	assertImageFits(t, img, 400, 300)
}

// assertImageFits decodes the image and checks it is inside the box resize was given, and that it
// touches one side of it, which is what fitting to a box rather than merely shrinking means
func assertImageFits(t *testing.T, data []byte, limitW, limitH int) {
	t.Helper()

	cfg, _, err := image.DecodeConfig(bytes.NewReader(data))
	require.NoError(t, err, "the resized image does not decode")

	assert.LessOrEqual(t, cfg.Width, limitW, "wider than the box it was resized into")
	assert.LessOrEqual(t, cfg.Height, limitH, "taller than the box it was resized into")
	assert.True(t, cfg.Width == limitW || cfg.Height == limitH,
		"%dx%d touches neither side of the %dx%d box, so it was not fitted to it", cfg.Width, cfg.Height, limitW, limitH)
}

func TestService_SaveTooLarge(t *testing.T) {
	svc := Service{ServiceParams: ServiceParams{ImageAPI: "/blah/"}}
	svc.MaxSize = 2000
	_, err := svc.Save("user2", io.MultiReader(gopherPNG(), gopherPNG()))
	assert.Error(t, err)
	assert.Contains(t, err.Error(), "is too large")
	err = svc.SaveWithID("test_id", io.MultiReader(gopherPNG(), gopherPNG()))
	assert.Error(t, err)
	assert.Contains(t, err.Error(), "is too large")
}

func TestService_WrongFormat(t *testing.T) {
	svc := Service{ServiceParams: ServiceParams{ImageAPI: "/blah/"}}

	_, err := svc.Save("user1", strings.NewReader("blah blah bad image"))
	assert.Error(t, err)
}

func TestService_ExtractPictures(t *testing.T) {
	svc := Service{ServiceParams: ServiceParams{ImageAPI: "/blah/", ProxyAPI: "/non_existent"}}
	html := `blah <img src="/blah/user1/pic1.png"/> foo
<img src="/blah/user2/pic3.png"/> xyz <p>123</p> <img src="/pic3.png"/> <img src="https://i.ibb.co/0cqqqnD/ezgif-5-3b07b6b97610.png" alt="">`
	ids := svc.ExtractPictures(html)
	require.Equal(t, 2, len(ids), "two images")
	assert.Equal(t, "user1/pic1.png", ids[0])
	assert.Equal(t, "user2/pic3.png", ids[1])

	svc = Service{ServiceParams: ServiceParams{ImageAPI: "https://remark42.radio-t.com/api/v1/picture/", ProxyAPI: "https://remark42.radio-t.com/api/v1/img"}}
	html = `<p>TLDR: такое в go пока правильно посчитать трудно. То, что они считают это общее количество go packages в коде.
</p>\n\n<p>Пакеты в го это средство организации кода, они могут быть связанны друг с другом в рамках одной библиотеки (модуля).
Например одна из моих вот так выглядит на libraries.io:</p>\n\n
<p><img src="https://remark42.radio-t.com/api/v1/picture/github_ef0f706a79cc24b17bbbb374cd234a691d034128/bjttt8ahajfmrhsula10.png" alt="bjtr0-201906-08110846-i324c.png"/></p>\n\n<p>
По форме все верно, это все packages, но по сути это все одна библиотека организованная таким образом. При ее импорте, например посредством go mod, она выглядит как один модуль, т.е.
<code>github.com/go-pkgz/auth v0.5.2</code>.</p>\n`
	ids = svc.ExtractPictures(html)
	require.Equal(t, 1, len(ids), "one image in")
	assert.Equal(t, "github_ef0f706a79cc24b17bbbb374cd234a691d034128/bjttt8ahajfmrhsula10.png", ids[0])

	// proxied image
	html = `<img src="https://remark42.radio-t.com/api/v1/img?src=aHR0cHM6Ly9ob21lcGFnZXMuY2FlLndpc2MuZWR1L35lY2U1MzMvaW1hZ2VzL2JvYXQucG5n" alt="cat.png">`
	ids = svc.ExtractPictures(html)
	require.Equal(t, 1, len(ids), "one image in")
	assert.Equal(t, "cached_images/12318fbd4c55e9d177b8b5ae197bc89c5afd8e07-a41fcb00643f28d700504256ec81cbf2e1aac53e", ids[0])
	require.Empty(t, svc.ExtractNonProxiedPictures(html), "no non-proxied images expected to be found")

	// bad url
	html = `<img src=" https://remark42.radio-t.com/api/v1/img">`
	ids = svc.ExtractPictures(html)
	require.Empty(t, ids)

	// bad src
	html = `<img src="https://remark42.radio-t.com/api/v1/img?src=bad">`
	ids = svc.ExtractPictures(html)
	require.Empty(t, ids)

	// good src with bad content
	badURL := base64.URLEncoding.EncodeToString([]byte(" http://foo.bar"))
	html = fmt.Sprintf(`<img src="https://remark42.radio-t.com/api/v1/img?src=%s">`, badURL)
	ids = svc.ExtractPictures(html)
	require.Empty(t, ids)
}

func TestService_Cleanup(t *testing.T) {
	synctest.Test(t, func(t *testing.T) {
		store := StoreMock{
			CleanupFunc: func(context.Context, time.Duration) error {
				return nil
			},
		}

		svc := NewService(&store, ServiceParams{EditDuration: 20 * time.Millisecond})
		// cancel context after 2.1 cleanup TTLs
		ctx, cancel := context.WithTimeout(context.Background(), svc.EditDuration/100*15*21)
		defer cancel()
		svc.Cleanup(ctx)
		assert.Equal(t, 2, len(store.CleanupCalls()))
	})
}

func TestService_Submit(t *testing.T) {
	synctest.Test(t, func(t *testing.T) {
		store := StoreMock{
			CommitFunc:            func(string) error { return nil },
			ResetCleanupTimerFunc: func(string) error { return nil },
		}
		svc := NewService(&store, ServiceParams{ImageAPI: "/blah/", EditDuration: time.Millisecond * 100})
		svc.Submit(func() []string { return []string{"id1", "id2", "id3"} })
		assert.Equal(t, 3, len(store.ResetCleanupTimerCalls()))
		err := svc.Commit(func() []string { return []string{"id4", "id5"} })
		assert.NoError(t, err)
		svc.Submit(func() []string { return []string{"id6", "id7"} })
		assert.Equal(t, 5, len(store.ResetCleanupTimerCalls()))
		svc.Submit(nil)
		assert.Equal(t, 2, len(store.CommitCalls()))
		time.Sleep(time.Millisecond * 175)
		assert.Equal(t, 7, len(store.CommitCalls()))
		svc.Close(context.TODO())
	})
}

func TestService_Close(t *testing.T) {
	store := StoreMock{
		CommitFunc:            func(string) error { return nil },
		ResetCleanupTimerFunc: func(string) error { return nil },
	}
	svc := Service{store: &store, ServiceParams: ServiceParams{ImageAPI: "/blah/", EditDuration: time.Hour * 24}}
	svc.Submit(func() []string { return []string{"id1", "id2", "id3"} })
	svc.Submit(func() []string { return []string{"id4", "id5"} })
	svc.Submit(nil)
	assert.Equal(t, 5, len(store.ResetCleanupTimerCalls()))
	svc.Close(context.TODO())
	assert.Equal(t, 5, len(store.CommitCalls()))
}

func TestService_SubmitDelay(t *testing.T) {
	synctest.Test(t, func(t *testing.T) {
		store := StoreMock{
			CommitFunc: func(string) error { return nil },
			ResetCleanupTimerFunc: func(string) error {
				return nil
			},
		}
		svc := NewService(&store, ServiceParams{EditDuration: 20 * time.Millisecond})
		svc.Submit(func() []string { return []string{"id1", "id2", "id3"} })
		time.Sleep(150 * time.Millisecond) // let first batch to pass TTL
		svc.Submit(func() []string { return []string{"id4", "id5"} })
		svc.Submit(nil)
		assert.Equal(t, 5, len(store.ResetCleanupTimerCalls()))
		assert.Equal(t, 3, len(store.CommitCalls()))
		svc.Close(context.TODO())
		assert.Equal(t, 5, len(store.CommitCalls()))
	})
}

func TestService_Info(t *testing.T) {
	store := StoreMock{InfoFunc: func() (StoreInfo, error) {
		return StoreInfo{}, nil
	}}

	svc := Service{store: &store, ServiceParams: ServiceParams{}}
	info, err := svc.Info()
	assert.NoError(t, err)
	assert.True(t, info.FirstStagingImageTS.IsZero())
	assert.Equal(t, 1, len(store.InfoCalls()))
}

func TestService_resize(t *testing.T) {
	t.Run("empty data returns nil", func(t *testing.T) {
		assert.Nil(t, resize(nil, 100, 100))
		assert.Nil(t, resize([]byte{}, 100, 100))
	})

	t.Run("non-image bytes are refused", func(t *testing.T) {
		// previously resize would fall back to the raw bytes on decode failure, letting
		// attacker-controlled non-image content reach the store. After hardening, refuse.
		assert.Nil(t, resize([]byte("some picture bin data"), -1, -1))
		assert.Nil(t, resize([]byte("invalid image content"), 100, 100))
	})

	cases := []struct {
		file   string
		wr, hr int
	}{
		{"testdata/circles.png", 400, 300}, // full size: 800x600 px
		{"testdata/circles.jpg", 300, 400}, // full size: 600x800 px
	}

	for _, c := range cases {
		img, err := os.ReadFile(c.file)
		require.NoError(t, err, "can't open test file %s", c.file)

		// no need for resize, image dimensions are smaller than resize limit
		resized := resize(img, 800, 800)
		assert.NotNil(t, resized, "file %s", c.file)
		assert.Equal(t, resized, img)

		// resizing to half of width
		resized = resize(img, 400, 400)
		assert.NotNil(t, resized, "file %s", c.file)
		imgRz, format, err := image.Decode(bytes.NewBuffer(resized))
		assert.NoError(t, err, "file %s", c.file)
		assert.Equal(t, "png", format, "file %s", c.file)
		bounds := imgRz.Bounds()
		assert.Equal(t, c.wr, bounds.Dx(), "file %s", c.file)
		assert.Equal(t, c.hr, bounds.Dy(), "file %s", c.file)
	}
}

// TestService_SaveWithIDShortPayload guards readAndValidateImage from panicking
// on a body shorter than 512 bytes — historically it sliced data[:512] without
// a bounds check, which would panic before any decode-bomb defense could fire.
func TestService_SaveWithIDShortPayload(t *testing.T) {
	short := []byte("not an image")

	svc := Service{ServiceParams: ServiceParams{ImageAPI: "/blah/", MaxSize: 1500, MaxWidth: 32, MaxHeight: 32}}
	err := svc.SaveWithID("test_id", bytes.NewReader(short))
	require.Error(t, err, "short non-image body must return an error, not panic")
	assert.Contains(t, err.Error(), "file format not allowed")
}

// TestService_SaveWithIDWebP confirms that WebP — listed as an allowed format
// in readAndValidateImage — still round-trips through prepareImage now that
// resize() runs image.DecodeConfig. Without registering the WebP decoder, a
// legitimate WebP upload would fail DecodeConfig and prepareImage would error.
func TestService_SaveWithIDWebP(t *testing.T) {
	webp, err := os.ReadFile("testdata/pixel.webp")
	require.NoError(t, err)

	// sanity: the fixture must be a well-formed 1x1 WebP that DecodeConfig accepts.
	cfg, format, err := image.DecodeConfig(bytes.NewReader(webp))
	require.NoError(t, err)
	require.Equal(t, "webp", format)
	require.Equal(t, 1, cfg.Width)
	require.Equal(t, 1, cfg.Height)

	store := StoreMock{SaveFunc: func(string, []byte) error { return nil }}
	svc := Service{store: &store, ServiceParams: ServiceParams{MaxSize: 1500}}

	err = svc.SaveWithID("webp_id", bytes.NewReader(webp))
	require.NoError(t, err, "valid WebP must round-trip through SaveWithID")
	assert.Equal(t, 1, len(store.SaveCalls()))
	assert.Equal(t, webp, store.SaveCalls()[0].Img, "no-resize path must return bytes verbatim")
}

// TestService_resizeRejectsDecompressionBomb verifies the dimension-cap defense.
// Builds a tiny GIF that declares 65535x65535 (4 gigapixels) in its logical-screen
// header — image.DecodeConfig reads the dimensions, the int64 product overflows
// any 32-bit int wrap, and resize must refuse before image.Decode allocates ~17 GB
// of pixel memory.
func TestService_resizeRejectsDecompressionBomb(t *testing.T) {
	// minimal GIF87a header with 65535x65535 logical screen, no global color table.
	// Bytes 6-7 are the little-endian width, 8-9 are the little-endian height.
	bomb := []byte{
		'G', 'I', 'F', '8', '7', 'a',
		0xFF, 0xFF,
		0xFF, 0xFF,
		0x00,
		0x00,
		0x00,
		0x3B,
	}
	cfg, _, err := image.DecodeConfig(bytes.NewReader(bomb))
	require.NoError(t, err, "bomb header must decode at the config level")
	assert.Equal(t, 65535, cfg.Width)
	assert.Equal(t, 65535, cfg.Height)

	assert.Nil(t, resize(bomb, 100, 100), "resize must refuse oversized dimensions before raster decode")
	assert.Nil(t, resize(bomb, 0, 0), "even with no-resize limits, oversized dims must be refused")

	// integration-level: SaveWithID must reject the same bomb without panicking
	// or allocating gigabytes of raster memory.
	store := StoreMock{SaveFunc: func(string, []byte) error { return nil }}
	svc := Service{store: &store, ServiceParams: ServiceParams{MaxSize: 1500}}
	err = svc.SaveWithID("bomb_id", bytes.NewReader(bomb))
	require.Error(t, err, "SaveWithID must reject decompression bomb")
	assert.Equal(t, 0, len(store.SaveCalls()), "rejected bomb must not be stored")
}

func TestGetProportionalSizes(t *testing.T) {
	tbl := []struct {
		inpW, inpH     int
		limitW, limitH int
		resW, resH     int
	}{
		{10, 20, 50, 25, 10, 20},
		{400, 200, 50, 25, 50, 25},
		{100, 100, 50, 25, 25, 25},
		{100, 200, 50, 25, 12, 25},
	}

	for i, tt := range tbl {
		t.Run(strconv.Itoa(i), func(t *testing.T) {
			resW, resH := getProportionalSizes(tt.inpW, tt.inpH, tt.limitW, tt.limitH)
			assert.Equal(t, tt.resW, resW, "width")
			assert.Equal(t, tt.resH, resH, "height")
		})
	}
}

func TestCachedImgID(t *testing.T) {
	img, err := CachedImgID(" http://foo.com")
	assert.Error(t, err)
	assert.Empty(t, img)
	imgURL := "http://example.org/img/1.png"
	img, err = CachedImgID(imgURL)
	assert.NoError(t, err)
	assert.Equal(t, "cached_images/"+Sha1Str("example.org")+"-"+Sha1Str(imgURL), img)
}

func TestService_DoubleClose(*testing.T) {
	store := StoreMock{}
	svc := NewService(&store, ServiceParams{EditDuration: 20 * time.Millisecond})
	svc.Close(context.TODO())
	// second call should not result in panic
	svc.Close(context.TODO())
}

// TestSafeImgContentType now lives in the rest package alongside the SafeImgContentType
// helper itself (see backend/app/rest/image_headers_test.go).